What might it mean to say that language is innate or, alternatively, that language must be learned? This proposal attempts to articulate these questions in terms that lend themselves to experimental investigation, asking which aspects of language development are so over-determined that they will appear even under learning conditions that vary widely from the norm. The participants are deaf children whose hearing parents have not yet exposed them to sign language, and whose hearing losses are so profound as to preclude acquisition of spoken language. Despite their lack of an accessible conventional language model, these children do communicate, developing gesture systems that are structured in language-like ways. Moreover, Chinese deaf children of hearing parents develop the same gesture systems as their American counterparts, suggesting that the deaf children's gesture systems are resilient, not only to the absence of a conventional language model, but also to cultural variation. Where do these deaf children's gesture systems come from? One candidate is the gestures hearing adults produce as they talk. Indeed, the gestures of Mandarin speakers are similar in type to those of English speakers. However, the gestures adults use when speaking languages typologically distinct from Mandarin and English - verb-framed languages such as Spanish or Turkish - differ strikingly from the gestures used by speakers of satellite-framed languages such as English or Mandarin. These four cultures thus offer an opportunity to examine effects of hearing speakers' gestures on the gesture systems developed by deaf children. If deaf children in all four cultures develop gesture systems with the same structure despite differences in the gestures they see, the children themselves must be bringing strong biases to the communication situation. The project has four aims: (1) To describe how adult speakers of Spanish or Turkish gesture differently from adult speakers of Mandarin or English. (2) To determine whether gesture systems created by Spanish and Turkish deaf children of hearing parents are structured as are gesture systems created by Chinese and American deaf children despite differences in the gestural models they see. (3) To describe how Spanish, Turkish, Chinese and American hearing children use gestures differently from deaf children in these same cultures even though they see hearing adults using the same gestures. (4) To determine whether Spanish, Turkish, Chinese and American hearing adults, when asked to use gesture as their sole means of communication, produce gestures structured like the deaf child's.